Monkeys infected with COVID-19 in China have developed antibodies to fight the coronavirus, a discovery that suggests the immune system will fight back against the disease, reports the South China Morning Post.

But researchers from the Chinese Academy of Medical Sciences also found animals could become infected through their eyes.

Professor Qin Chuan wrote on bioRxiv, a website for studies pending peer review, that his research team infected four monkeys with the COVID-19 strain. The animals started to show symptoms three days later.

On the seventh day of the experiment, Qin euthanized one of the monkeys found that the virus had spread throughout its body, "from nose to bladder with visible damage to the lung tissues."

The rest of the monkeys recovered. About a month later, two monkeys were dosed with the virus again.

Their temperatures rose, but no other symptoms were recorded. Autopsies performed on the monkeys about two weeks later found no trace of the virus, and high antibody levels were detected.

The results would have "important implications in evaluating vaccine development," Qin wrote on bioRxiv.

The report comes as a lab in Cambridge, Massachusetts, Moderna, has developed the first experimental coronavirus medicine, and the first human trial testing a potential vaccine to prevent COVID-19 started.

There are no proven therapies for the outbreak, which has killed at least 6,513 and sickened nearly 170,000 people worldwide since emerging from the Chinese city of Wuhan less than three months ago.

Monkeys infected with COVID-19 in China have developed antibodies to fight the coronavirus, a discovery that suggests the immune system will fight back against the disease, reports the South China Morning Post.